Method and apparatus for forming pulpwood chips

ABSTRACT

A wood chipper has a guiding tunnel from a rotating chipper disc to a fanwheel spaced from the disc for guiding chips into the path of blades of the fanwheel in substantial parallelism with the path of the blades and at a velocity not greatly different from that of the blades.

United States Patent [191 Keating I 1 July 31, 1973 [54] METHOD ANDAPPARATUS FOR FORMING 3,661,329 5/1972 Smith 244/176 X PULPWOOD CHIPS3,635,410 l/l972 Smith 3,384,311 5/1968 Eklund et al. 144/176 X [75]Inventor: James L. Keatlng, Milwaukie, Oreg.

73 Assi nee: R derC l l P l d l 1 8 ot g on an Primary Eqqminer-DonaldR. Schran Attorney-Stephen W. Blore, Kenneth S. Klarquist [22] Filed:Oct. 26, 1971 et a1.

[21] Appl. No.: 192,037

[57] ABSTRACT [52] US. Cl 241/28, 144/176, 241/56,

8 R A wood chipper has a guiding tunnel from a rotating [51] Int. ClB271 11/02 chi er disc to a fanwheel spaced from the disc for [58] Fieldof Search 144/176, 162 R; guiding chips into the path of blades of thefanwhee i 241/56, 51, 278 R, 92, 28 substantial parallelism with thepath of the blades and at a velocity not greatly different from that ofthe [56] References Clted blades.

UNITED STATES PATENTS Smith 241/56 9 Claims, 4 Drawing Flgures PAIENIEBM 3.749.323

SHEET 1 OF 2 JAMES L. KEATING INVENTOR BUCKHORN, BLORE, KLARQUIST &SPARKMAN ATTORNEYS PATENIED m3] ms SHEET 2 0F 2 FIG. 2

JAMES L. KEATING INVENTOR BUCKHCRN, BLORE, KLARQUIST & SPARKMANATTORNEYS METHOD AND APPARATUS FOR FORMING PULPWOOI) CIIIPS BACKGROUNDOF THE INVENTION In the making of paper pulp from wood, and particularlyin utilizing a chemical pulping process, it is desirable that the woodchips be uniform in size both in width and length as well as inthickness, and that the chips have a minimum content of slivers or pinsand sawdust-like particles that will pass, for example, a three-eighthinch screen.

To obtain wood chips of the desired size it is conventional practice topass logs or wood scraps through a chipper which comprises a massiverotating disc having radially extending knives arranged to cut off theends of the wood or logs fed into the chipper so that chips ofpredetermined length are formed. The disc on which the knives aremounted is provided with passageways so that the severed chips may passto the rear of the disc. For practical reasons chippers are constructedso that the knives impact upon the log or wood as the knives arerotating substantially downwardly. The chips will have high velocityimparted to them by reason of the impact of the knife upon the woodbeing cut and their trajectory will be in a generally downward andrearward direction. Chippers are in two general classes with respect totheir discharge, namely bottom discharge and top discharge, the termsbeing descriptive of the location at which chips are taken from thechipper housing. In a top discharge chipper it is necessary to changethe direction of the chips from their general downward direction andcause them to be moved upwardly and through the outlet at the top of thehousing. Such change of direction is generally done by placing bladesupon the back and periphery of the cutter disc for engaging andpropelling the chips. The geometry of prior chippers has been such thatthe blades have engaged the chips at a relatively high differentialvelocity with substantial damage to the chips and production of largeamounts of slivers and pins and sawdust-like particles. In addition totheir impingement upon the blades, the prior chippers have presentedsurfaces such as the fanwheel itself, for example, against which thechips can impact at a high velocity and at a large incidence angleresulting in further breakage of the chips.'

BRIEF DESCRIPTION OF THE INVENTION It is an object of the presentinvention to provide a configuration for a top discharge chipper whereinthe chips are introduced into a discharge air stream substantially inparallel to the air stream.

The chipper of the invention comprises a rotary cutter disc with theusual substantially radial knives for cutting chips from a log or woodpieces fed to the disc. Mounted rearwardly of the cutter disc is afanwheel having impeller blades on the periphery for engaging andpropelling chips. The cutter disc and fanwheel are surrounded bysuitable housing means enclosing and providing protection of each, thehousing portion about said fanwheel forming a centrifugal fan with thefanwheel and having a chip discharge opening in the top. The housingmeans has a funnel-like tunnel for intercepting and gathering the chipsfrom the chipper and directing the chips into the blade path of thefanwheel in near parallelism with the blade path.

In the drawings:

FIG. 1 is a perspective view of a chipper constructed in accordance withthe invention;

FIG. 2 is a horizontal section taken substantially along line 2-2 ofFIG. 1;

FIG. 3 is an enlarged fragmentary elevation of a chipper takensubstantially along line 33 of FIG. 2; and,

FIG. 4 is a schematic view of the chipper of FIG. 1.

DETAILED DESCRIPTION OF THE INVENTION The illustrated chipper comprisesa chipper disc 12 mounted on a horizontal shaft 14 driven from asuitable motor (not shown). The shaft 14 is shown as supported intrunnions 16 mounted on a suitable supporting base 18 and is otherwisesuitably supported. The illustrated chipper is of the horizontal infeedtype and is illustrated as having an infeed spout 20 extending throughan opening 22 in the base 18. As will be apparent, the invention isequally applicable to chippers having a vertically inclined feed spout.

The cutter disc I2 is enclosed within a protective coaxial housing 24,the front wall 26 of which is provided with an opening 28 communicatingwith the spout 20. One wall of the opening 28 defines a vertical anvil30 and the bottom edge defines a horizontal anvil 32 against which a logor board 33 is pressed as it is engaged by the knives on the cutterdisc.

The chipper disc 12 may be of any conventional construction and isprovided with a plurality of removably mounted knives 36 which projectfrom the front face thereof, the disc having openings or slots 38adjacent to each of the knives through which severed chips may pass fromthe front to the back of the disc 12. The knives 36 of the illustratedchipper are offset from but parallel to radii of the disc 12, but, aswill be apparent, the invention is equally applicable to chippers usingthe more conventional arrangement wherein the knife edges extend alongradii of the disc.

Mounted on the shaft 14 rearwardly of the disc I2 with respect to theposition of the spout 20 is a fanwheel 40 provided with a plurality ofimpeller blades 46. The fanwheel 40 is surrounded by a housing 42defining a scroll case having a tangential outlet 44 at the top thereof.Extending between and communicating with the disc housing 24 and thefanwheel housing 42 is a guide or tunnel which intercepts, gathers anddirects the chips from the cutter disc 12 into the housing 42 insubstantial parallelism with the path of the blades 46, which is thepath of the air stream created by the blades.

The tunnel 50 has a bottomwall or surface 52 to receive and direct thechips almost tangentially into the air stream created by the blades. Theentrance portion 53 of surface 52 is planar and horizontal and thedischarge end portion 55 is upwardly curving. The tunnel 50 also has aside wall 54 including a planar portion 47 almost parallel to the pathof the log at the entrance end of the tunnel and a curved discharge endportion 49 which at its end is substantially parallel to the plane ofthe fanwheel at discharge opening 56 of the tunnel. A stiffening flange57 is provided at the upper edge of the planar portion, and stiffeners59 and 61 secure the tunnel rigidly in the housing. The chips aredischarged from the knives 36 in a stream impinging against the bottomsurface 52 and the side surface 54 at angles less than 45 so that thereis little or no fracturing of the chips and the velocity of the chips isreduced very little. The tunnel directs the stream of chips into the airstream of the fanwheel at a small angle with the air stream and with thechips having a velocity almost as great as that of the fan blades 46,for example, within about fifteen per cent of the speed of the fanblades. As a result, the air stream and momentum of the chips takes mostof the chips out of the housing without engagement with the fan bladesand those chips which are engaged by the fan blades are engaged at sucha low differential velocity that there is substantially no fracturing ofthe chips. Also, as best shown in FIG. 3, the almost tangential entrancedirection of the chips causes them to impinge against the periphery ofthe fanwheel housing 42 at such a small angle that the chips are notfractured and are not slowed appreciably.

The chips are discharged through the outlet 44 which may be connected toany suitable conveying system. The velocity of the chips as theydischarge from the outlet 44 will be such that they are transported bythe air stream a substantial distance.

What is claimed is:

1. In a top discharge chipper,

a shaft,

a chipper disc mounted on the shaft and rotated thereon for slicingchips crosswise of the grain from the ends of a log fed thereto anddischarging chips in a predetermined path,

a fanwheel mounted on the shaft at the discharge side of the chipperdisc and spaced from the chipper disc, and intersecting said chips path,

a fan housing having a discharge opening and defining a centrifugal fanwith the fanwheel, whreby the fan creates a generally peripheral airstream flowing to and through the discharge opening,

first deflecting means fixed relative to the fan housing, arranged tointercept said chips at an impact angle less than about 45 and directingthe chips substantially radially outwardly to prevent impingement of thechips against the fanwheel,

and second deflecting means fixed relative to the fan housing, arrangedto intercept said chips at an impact angle less than about 45 anddeflecting the chips substantially tangentially into the air stream' 2.The top discharge chipper of claim 1 wherein the first deflecting meansis a first wall in a position positioned between the chipper disc andthe fanwheel to prevent impingement of the chips on the fanwheel.

3. The top discharge chipper of claim 2 wherein the first wall curvesfrom a direction extending acutely relative to the fanwheel to adirection extending substantially parallel to the fanwheel proceedingaway from the entrance end of the wall toward the discharge end of thewall.

4. The top discharge chipper of claim 3 wherein the second deflectingmeans is a second wall substantially perpendicular to the first wall.

5. The top discharge chipper of claim 4 wherein the second wall curvesto a direction almost tangential to the peripheral portion of thefanwheel at the discharge end of the second wall.

6. The top discharge chipper of claim 5 wherein the walls define atrough substantially L-shaped in transverse cross-section.

7. In a top discharge chipper,

a shaft,

a chipper disc mounted on the shaft and rotated thereby for slicingchips crosswise of the grain from the end of a log fed thereto anddischarging the chips in a predetermined path,

a fanwheel mounted on the shaft at the discharge side of the chipperdisc and spaced from the chipper disc, and intersecting said path,

a fan housing having a discharge opening and defining a centrifugal fanwith the fanwheel, whereby the fan creates a generally peripheral airstream flowing to and through the discharge opening, and a generallyfunnel-like guide leading from the discharge area of the chipper discsubstantially to the air stream providing impact surface for said chipsat an angle less than about 45 and directing chip flow substantiallytangentially into the air stream.

8. In a top discharge chipper,

a fanwheel having a peripheral blade portion,

a fan housing enclosing the peripheral blade portion of the fanwheel andalso having a discharge opening to define a centrifugal fan,

a chipper disc having blades for slicing chips crosswise of the grainfrom the end of a log fed thereto and discharging chips toward thefanwheel,

first deflector means fixed relative to the fan housing, positionedadjacent the fanwheel for intercepting the discharged chips at an angleless than about 45 and directing the chips radially outwardly away fromthe fanwheel,

and second deflecting means fixed relative to the fan housing,intercepting the discharged chips at an angle less than about 45 and fordirecting the chips at a small angle into the path of the fanwheel.

9. The method of producing wood chips comprising:

slicing chips crosswise of the grain from the end of a log, whereuponthe chips are discharged at least partially toward a portion of acentrifugal fanwheel positioned radially inwardly from the bladeportions of the fanwheel at a high velocity,

and intercepting the discharged chips at a small angle and guiding thechips along a fixed path radially outwardly relative to the fanwheel andinto the path of the blade portions in a direction substantiallyparallel to the direction of movement of the blade portions, wherebybreakage of the chips is minimized.

i It i I t

2. The top discharge chipper of claim 1 wherein the first deflectingmeans is a first wall in a position positioned between the chipper discand the fanwheel to prevent impingement of the chips on the fanwheel. 3.The top discharge chipper of claim 2 wherein the first wall curves froma direction extending acutely relative to the fanwheel to a directionextending substantially parallel to the fanwheel proceeding away fromthe entrance end of the wall toward the discharge end of the wall. 4.The top discharge chipper of claim 3 wherein the second deflecting meansis a second wall substantially perpendicular to the first wall.
 5. Thetop discharge chipper of claim 4 wherein the second wall curves to adirection almost tangential to the peripheral portion of the fanwheel atthe discharge end of the second wall.
 6. The top discharge chipper ofclaim 5 wherein the walls define a trough substantially L-shaped intransverse cross-section.
 7. In a top discharge chipper, a shaft, achipper disc mounted on the shaft and rotated thereby for slicing chipscrosswise of the grain from the end of a log fed thereto and dischargingthe chips in a predetermined path, a fanwheel mounted on the shaft atthe discharge side of the chipper disc and spaced from the chipper disc,and intersecting said path, a fan housing having a discharge opening anddefining a centrifugal fan with the fanwheel, whereby the fan creates agenerally peripheral air stream flowing to and through the dischargeopening, and a generally funnel-like guide leading from the dischargearea of the chipper disc substantially to the air stream providingimpact surface for said chips at an angle less than about 45* anddirecting chip flow substantially tangentially into the air stream. 8.In a top discharge chipper, a fanwheel having a peripheral bladeportion, a fan housing enclosing the peripheral blade portion of thefanwheel and also having a discharge opening to define a centrifugalfan, a chipper disc having blades for slicing chips crosswise of thegrain from the end of a log fed thereto and discharging chips toward thefanwheel, first deflector means fixed relative to the fan housing,positioned adjacent the fanwheel for intercepting the discharged chipsat an angle less than about 45* and directing the chips radiallyoutwardly away from the fanwheel, and second deflecting means fixedrelative to the fan housing, intercepting the discharged chips at anangle less than about 45* and for directing the chips at a small angleinto the path of the fanwheel.
 9. The method of producing wood chipscomprising: slicing chips crosswise of the grain from the end of a log,whereupon the chips are discharged at least partially toward a portionof a centrifugal fanwheel positioned radially inwardly from the bladeportions of the fanwheel at a high velocity, and intercepting thedischarged chips at a small angle and guiding the chips along a fixedpath radially outwardly relative to the fanwheel and into the path ofthe blade portions in a direction substantially parallel to thedirection of movement of the blade portions, whereby breakage of thechips is minimized.